This was a "fun" topic. I never did figure this out. I put on about 40K km on the car, and it did it from the moment I picked it up, to the moment I dropped it off. Had no effect on the performance or reliablity of the car. Car ran just as good when it left my hands as it did when I picked it up. I threw quite a bit of money at the issue, and lots of effort and could never figure it out fully. Some times is happened, other times not. Most of the time it did. To those that say its "normal"... Its not. Its very distinct, and NOT the noise the alternator clutch makes when you fire up the car. That noise is normal. This is not.

The good news is the new owner of the vehicle is A LOT more knowledgable then I. BMW shop owner and the whole bit. He's on it now, but I have a feeling that he will just end up swapping the motor as he has access to used parts at a fraction of the cost that I would end up paying

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I waited about 2 weeks before posting this update, just to be sure, but:

After doing the rod bearings, engine mount (one was blown) and changing the oil pump chain tensioner, the situation has improved remarkably:

I have cold started the car about 20 times over the last two or so weeks, and 75% of the time, the noise is not there, and times when it is, its so quiet I probably wouldn't notice it with the windows up.

Here is a video from this morning, when it appears, this is what it sounds like. A single CLUNK rather then a successive clunk-clunk-clunk (see videos below) like before.

I can live with this.

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I know this has been discussed a few times before, but I wonder if anyone had found a solution to this.

I have uploaded 2 videos.

I understand that a slightly noisy vanos for a second or so on cold start is normal as oil pressure needs to build up.

I am not talking about that, I am talking about the noise at 0:03 on the first video and at 0:04 on the 2nd.

Anyone have an idea of what this is?

A) ONLY happens on cold start. But even if it has sat for as little as 4 hours. Also worth mentioning, even if I "cold start" the car, wait 2 seconds, turn it off, and back on again, the noise will not happen again until next cold start (a few hours later).

B) Happens on EVERY cold start.

C) NEVER happens otherwise.

D) Car runs perfectly otherwise.

E) E92 M3, production 2007.07.

F - Update) Car has bpmsport.com tune with cold start delete enabled. So this is not related to the secondary air pump as this was happening before and after. Car also has 240E installed, previously had 50E. Noise was / is present on both.

J - Update #5) Check valves on order, install early next week. Will report if it helps or not.

K - Update #6) Check valves changed, unfortunatly due to time, only 3 of 4 (last one gonna be done next early next week). Also, new development, engine temperature HAS an influence on if / how loud the noise is ( http://www.m3post.com/forums/showpos...7&postcount=69 ). Waiting 12+ hours as I write this update before testing if the check valves help or not.

L - Update #7) Previous "run cycle" temperature has a clear effect on the loudness of the noise. If on previous start / stop the motor / oiil doesnt warm up, the next time the noise is expected (6+ hours later), the noise is almost not there. See post video in post #84 ( http://www.m3post.com/forums/showpos...5&postcount=84 ).

M - Update #8) I was unable to determine exactly where the noise was coming from when I listened for it with the intake manifold off + my head under the hood. It *SOUNDED* like it was coming from under the drivers side valve cover area.

O - Update #9) The following were replaced: check valves and chain tensioners. The starter was pulled, cleaned and greased. The noise still persists. In my case, I can say for sure, the 3 listed are NOT responsible for the noise.

P - Update #10) Changed over to 0W40. Did not fix it, noise still there but noticeably better. 1/4 the time the noise doesnt happen, and after 20+ cold starts (a couple weeks worth at least) i have yet to hear it long and loud like numerous times before. This points me to this being somewhere within the oil system.

Q - Update #11) Tried having BPM code me a tune with the idle raised. Thought that a raised idle would lubriicate the motor a bit more just prior to shut down. Nope..... Noise still there.

R - Update #12) My car is 6MT. I coded my car from requiring the clutch to be pressed before the motor will be allowed to start, to forcing the break. Seams to have helped a bit, but the noise is still there.

S - Update #13) I tried running a bottle of CeraTec thru the motor, and on next oil change MOS2. Noise still there.

T - Update #14) There is a parameter in the CAS: "DELAY_KL50L. START DELAY FOR ENGINES WITH VALVETRONIC. VARIABLE VALVE TIMING". I tried changing this. No dice, noise still there.

But after going thru all dozen or so pages of it... No concrete solution was found

I'm guessing it could be one of the following:

A) Like you said, late starter disengaging.
B) Something to do with lack of oil pressure after the car has been sitting for a bit (check valves?).
C) Vanos belt tensioner letting the vanos chain go slack after the car has been sitting for a bit.

Would really like to get this fixed, but dont want to start throwing arrows in the dark only to find the noise still present

I will say that your example sounds a bit more "advanced" than I've heard elsewhere and on my own M3s. The rattle/grind begins almost right as the motor turns over instead of on slight delay. How long has this been happening for you?

On the bright side, if everyone on the forum starts one of these threads we can establish normalcy.

Here also > http://www.m3post.com/forums/showthread.php?t=987126
In the OP second video i can hear the clunk noise and at the same time a metallic rattle !
First time that i hear the rattle in it !
Now in my posted link someone said i tap my brakes 6-7 times and hold the brake pedal about 30 secondes,now i have done this too and the clunk is gone when i start the car !
Now my question is....what the hell has the brake to do with the clunk noise ?!?!
And the mystery about the clunk noise goes on and on and ......................damn this noise ?!?!

In about 2 hours I will head down to the underground and try tapping the break numerous times, and then holding as I start the vehicle and let you know if this happens or not.

For what its worth, mine is 6MT btw...

Quote:

Originally Posted by ///M Power-Belgium

Here also > http://www.m3post.com/forums/showthread.php?t=987126
In the OP second video i can hear the clunk noise and at the same time a metallic rattle !
First time that i hear the rattle in it !
Now in my posted link someone said i tap my brakes 6-7 times and hold the brake pedal about 30 secondes,now i have done this too and the clunk is gone when i start the car !
Now my question is....what the hell has the brake to do with the clunk noise ?!?!
And the mystery about the clunk noise goes on and on and ......................damn this noise ?!?!

In about 2 hours I will head down to the underground and try tapping the break numerous times, and then holding as I start the vehicle and let you know if this happens or not.

For what its worth, mine is 6MT btw...

Perfect man ! Mine is DCT , and the other guy with tapping the brake has also DCT !
Please keep us posted,i realy...realy would love a solution for the clunk noise ,for the moment the only thing that works for me personal is tapping the brake pedal and i know it sounds realy unbelievable,but it works !
BTW.....like others are saying Mike (Mike-Benvo) hears it all over the world when tuning our cars(remote cable tuning) on Skype !
I know he's engine did it too,but now with the new engine he got i don't know,and i need to ask him about it !
Damn the clunk noise ?!?!

Doesn't "normal" imply that they all do it? Mine doesn't; never heard any strange noises following start-up in everyday use, though it can happen after an oil change. I forgot to pre-fill the oil filter and got a significant noise 2 seconds after the first start-up with fresh 10W-60 oil.

I bought the car about 2.5K km ago... Its been happening ever since I bought it

The previous owner (a close friend) has had it happening since he bought it as well.

Car has about 67K km on it.

I posted this video now 3 times on this forum ,and so here is it again to make this clunk noise very....very clear !
Note : This is not my car and actualy it is "the loudest clunk noise" i ever heard from our S65 engine !

Pesonal i think when looking at your noise and clunk noise graphics through the spectrum analyzer it's not the starter ,it comes later when engine starts to run !
It is also in this way when i hear it on mine !
Note ; Like i said yesterday this thread (link of ) is now at my BMW/Dealer,last year my car was a few times there for this problem but my engine did not make the clunk noise, because it drove the car to my dealer and was warmed up !
And i'm waiting now for answers ,because they are looking into the Puma-Database...... i'm curious and let's hope !
Will post the result as soon when i receive it !

I can't imagine why you guys go to the lengths you do.. Analyzing the noise via spectrum analyzer, lol!!!

This is a normal noise and probaly due to some check valve that allows the oil to drain back overnight or when the car sits. Think about when you change you oil. Unless you prime the motor (crank w/out starting to build oil pressure) the first start after an oil change makes some noise as the engine has no oil in it for a split second until it's running.

Yes, the noise is annoying, but it is what it is (BTW both my M3 have done this)